Today, synthetic chemicals, such as colorants or cross-linking reagents, tend to have decreasing acceptance in the food, cosmetic, animal feed and textile industries. For safety reasons, whether real or perceived, people tend to favor the use of natural or organic ingredients in food, cosmetic, textile, and biomaterial products.
Genipin is a colorless compound. It belongs to the iridoid group. It is very active chemically and reacts immediately when combined with compounds having primary amine groups, such as amino acids, collagen, chitosan, glucosamine-type compounds and various proteins and enzymes. When oxygen is present, the product may turn to blue, green, or black quickly. Genipin is an iridoid ester, therefore, it can be hydrolyzed to generate genipinic acid which also can react with different compounds to generate red and brown colorants. The colorants generated from genipin are heat and pH stable. Since genipin normally comes from plant materials, its Kosher characteristics provide great potential for use of genipin-derived colorants in bakery and canned food applications.
Large amount of iridoids, such as geniposide, gardenoside, genipin-1-b-gentiobioside, geniposidic acid and genipin, can be found in Gardenia jasminoides Ellis fruit. Geniposide, an iridoid glycoside, is a main component comprising 7-8% of fruit weight, while only trace amounts of genipin naturally exist in the Gardenia fruit. Historically, the iridoids in Gardenia fruit were extracted from the fruit with methanol or ethanol, and then separated as yellow pigment on active carbon, and treated with enzymes having beta-glucosidic activity or proteolytic activity to convert glycoside iridoids to aglycone form, genipin or genipinic acid. Then, genipin or genipinic acid can be reacted with other compounds to produce colorants (KR1020010096213A).
Genipin and other iridoid compounds, such as genipinic acid, genipin-gentiobioside, geniposide and geniposidic acid, are found also in the fruits and leaves of Genipa americana, also known as Genipap, or Huito, a tropical wild plant. Genipin is naturally present in the mature fruit, and its quantity is from 0 to 3.0% of fruit weight depending on the degree of ripeness. Genipin is stable in the plant cell even though it is not established where it is stored. Whenever the cell is broken, genipin will react spontaneously with the amino acids that naturally exist in the fruit pulp and turn color to blue or black in an air environment. In our previous patent application (US20090246343A1), we made coloring (blue) fruit juice by mixing Genipa americana fruit pulp with juices from other fruits or vegetables. The natural acid-stable blue juice has been used broadly in the food and beverage industries. Lopes et al. (U.S. Pat. No. 7,927,637B2) used unprocessed raw juice obtained from Genipa americana fruit pulp, and mixed with glycine or with glycine plus starch, to make blue colorants. Patrice Andre and co-worker (US20100196298A1) used coloring materials obtained from the plant extraction of Genipa americana, Gardenia jasminoides, Rothmannia, Adenorandia or Cremaspora, bound to a solid substrate, to make cosmetic compositions.
Genipin not only can generate colorants, but also can act as a good cross-linking agent. Campbell et al. discovered a new biodegradable plastic polymer involving genipin as cross-linking agent (EP2093256A2). Such plastics are useful in biological systems for wound repair, implants, stents, drug encapsulation and delivery, and other applications. Fujikawa et al. claimed (U.S. Pat. No. 4,983,524) the use of iridoid aglycone, genipin, as a cross-linking agent to produce immobilized enzyme on beads for food industry. Quijano, R and Tu, H (US 20080195230A1) disclosed the use of genipin to fix whole, natural tissues to reduce antigenicity and immunogenicity and prevent enzymatic degradation of the tissue when implanted in a host.
However, pure genipin production historically involves many steps, including HPLC separation, and currently its cost is high. No description in the art teaches the preparation of a stable genipin-rich extract from Genipa americana plant, and its broad applications as natural colorants and cross-linking agent in foods, drugs, nutritional supplements, personal care products, cosmetics, animal feed, textiles, polymers, and in the biomaterial industries.